The present invention pertains to an indicator for producing an audible sound to indicate the type of a vapor passing through the indicator and in particular to a indicator useful for distinguishing between differing gases, especially an unknown vapor and gases commonly found in the atmosphere. The indicator of the present invention, while useful in distinguishing vapors from atmosphere is particularly useful in separating them from refrigerant gases.
It is widely believed today that refrigerants, typically chlorofluorocarbons (CFC), used in vapor compression cooling and heat pump systems have a detrimental effect on the earths' atmospheric ozone layer when the refrigerant is released from a cooling system into the atmosphere. When servicing or repairing a cooling system, it is often first necessary to remove the refrigerant from the cooling system. In the past, refrigerant typically has been released to the atmosphere rather than recovered for later use. The low cost and ready availability of new refrigerant makes it difficult for a service technician to justify the time and expense necessary to recover the refrigerant for later reuse.
However, with the growing concern over the detrimental effect of releasing CFC refrigerants into the atmosphere, new regulations are being passed that prohibit the release of CFC refrigerants into the atmosphere. Rising cost for CFC refrigerants and increased taxation on the production of CFC refrigerants has produced an economic incentive for service technicians to recover the refrigerant rather than releasing it into the atmosphere.
Many refrigerant retrieval devices have been developed in recent years precisely for this purpose. Two such devices are disclosed in Applicant's copending patent applications, Ser. No. 593,689 filed Oct. 5, 1990 and Ser. No. 643,527 filed Jan. 18, 1991. These devices, as well as virtually all other refrigerant retrieval devices, ultimately collect the refrigerant in a closed vessel in which the refrigerant is stored in a steady state condition in which the refrigerant exists as both liquid and vapor. Often times though, a small quantity of non-condensible gas such as air or nitrogen will also be present within the closed vessel. Before returning the recovered refrigerant into the cooling system, it is essential that these non-condensible gases be removed from the closed vessel to avoid the introduction of the non-condensible gases into the cooling system. Typically, the non-condensible gas is removed by opening the closed vessel to allow the gas to vent therefrom. In order to ensure that all of the non-condensible gas is removed, the closed vessel is typically vented longer than necessary with the result that CFC refrigerants are also vented from the closed vessel to the atmosphere. Without rather costly and complex equipment it is impossible for the service technician to ensure that all of the non-condensible gases have been vented without also venting an unknown quantity of the CFC refrigerant as well.
The term "non-condensible" is used in the specification and claims in reference to gases such as air, nitrogen, carbon dioxide, etc which do not condense at ambient temperatures or temperatures experienced in a cooling system cycle as distinguished from refrigerants which are readily condensible at these temperatures.
Accordingly, it is an object of the present invention to provide a vapor type indicator to immediately signal to the technician when all of the non-condensible gases have been vented and that the refrigerant is now being released.
It is a feature of the present invention to provide a device in which the vapor being vented from the closed vessel passes a whistle that will produce an audible signal. The pitch of the signal is a function of the density of the vapor flowing through the device. Due to the density differences between the non-condensible gases present in the closed vessel and the refrigerant vapor, a noticeable difference in pitch can be observed when the gas flowing through the indicator changes from the non-condensible to the refrigerant.
It is a further feature of the present invention to provide a chamber of air that will vent past the whistle first to ensure that initially there will be a gas other than the refrigerant producing the whistle. When the refrigerant is later vented past the whistle, a noticeable change in pitch will occur.
The indicator can be equipped with an electronic pitch detector that electronically detects the change of pitch from the whistle and provides a signal indicating when this has occurred. This embodiment can further be provided with a electronic shut-off valve to stop the flow of vapor from the closed vessel when the pitch change has occurred.
With the appropriate controls for the internal pressure of the closed vessel as well as the temperature of the refrigerant therein, the indicator can be used to determine what type of refrigerant is present. An electronic pitch recognition device is used which not only can distinguish between two different pitches but can determine the frequency of the pitch. With the necessary control for the system pressure and temperature, each refrigerant will produce a different frequency pitch that can be used to determine the type of refrigerant encountered. This is particularly useful in a number of situations.
An example of one such situation is the servicing of a motor vehicle cooling system. Automobile cooling systems are now being produced that use R-134 as a refrigerant rather than the more harmful R-12 refrigerant previously used. When servicing a cooling system it is necessary to ensure that R-12 and R-134 are not mixed together and that when charging a system that the proper type of refrigerant is added to the refrigerant remaining in the system. Previously, it was possible to distinguish between refrigerants by noting the pressure and temperature of the refrigerant and comparing that information to well known charts for each refrigerant. However, R-12 and R-134 produce very similar temperature versus pressure profiles. With a small amount of a non-condensible gas present, it can be impossible to distinguish between these refrigerants without first totally assuming that all non-condensibles have been removed. Furthermore, the pitches produced by these gases vary significantly such that the acoustic vapor indicator of the present invention can with the aid of electronics, be easily used to detect which refrigerant is present.
A further use of a device that can identify the type of refrigerant is in a refrigerant reprocessing facility where a number of storage containers are present and it is necessary to properly identify each refrigerant. To ensure that bottles are not mismarked or in the event a bottle is not marked at all, a simple refrigerant analyzer is required to determine which refrigerant is present before the bottles are emptied.
Alternatively, a microprocessor having preprogrammed information regarding the frequency produced by various refrigerants at a variety of temperatures and pressures can be used to determine the type of refrigerant vapor present. This avoids the need for controlling the temperature and pressure of the refrigerant vapor.
The acoustic vapor type indicator of the present invention provides a simple and easy to use device for detecting the presence of a refrigerant and also the potential to identify the type of refrigerant.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.